The European Space Agencyโsย Euclid space telescope has identified 31 extremely ancient quasars, offering astronomers a deeper look into the early universe. Among these discoveries are two of the oldest quasars ever observed, dating back to a time when the universe was only about 670 million years old, roughly 5% of its current age.
Quasars are among the brightest objects in the cosmos. They occur during a short but powerful stage in the life of a galaxy, when huge amounts of gas and dust fall into a central supermassive black hole. As this material spirals inward, it heats up and releases intense radiation, causing the galaxyโs core to shine hundreds or even thousands of times brighter than the rest of the galaxy.
For decades, astronomers have searched for the earliest quasars because they provide valuable clues about the formation of the first galaxies and the rapid growth of supermassive black holes. However, finding quasars from the universeโs infancy is extremely difficult. They are rare, very distant, faint, and can easily be mistaken for nearby stars.
Euclid, which was launched in 2023, is now helping scientists explore this distant period of cosmic history more effectively. With its wide-field view and powerful infrared observations, the telescope has uncovered an unusually large group of ancient quasars from a time when the universe was still very young.
According to Daming Yang of Leiden University in the Netherlands, lead author of the discovery paper, these early quasars allow scientists to investigate how massive black holes and galaxies formed and expanded so rapidly in the early universeโone of the major unanswered questions in astrophysics.
Looking Beyond the Brightest Ancient Quasars
Before Euclidโs new discovery, astronomers had only identified a small number of very bright quasars from the early universe. These were the easiest to detect, but they represented only a limited part of the ancient quasar population.
Euclidโs observations are changing that picture. The telescope is not only detecting the brightest objects but is also revealing fainter quasars across large areas of the sky. This gives scientists a broader and more complete view of quasar activity in the universeโs first billion years.
The new discovery includes 12 quasars with redshifts of 7 or higher. Redshift is a measure used by astronomers to estimate how far away an object is and how much the universe has expanded since the objectโs light began travelling toward us. A redshift of 7 or above means the light comes from a period within the first 770 million years after the Big Bang.
The two most distant quasars in the group are named EUCL J172902.75+641018.1 and EUCL J125308.55+705432.3. They have redshifts of 7.77 and 7.69, respectively, making them the oldest quasars currently known. Both are located more than 13 billion light-years away and were already shining when the universe was just 670 million years old.
ESA research fellow Antonio La Marca noted that this discovery more than doubles the number of quasars known from such an early period. Finding the first few quasars at redshift 7 or higher took astronomers more than ten years, but Euclid has found more than that in only one year of observations.
For the first time, the Euclid team has been able to carry out something close to a census of quasars from the dawn of the universe. This is an important step toward understanding these rare and powerful objects as a population, rather than as isolated discoveries.
A Window Into a Turning Point in Cosmic History
The quasars discovered by Euclid come from a major era in the history of the universe known as the epoch of reionization. During this period, the universe changed from a cold and dark state into one filled with hot, ionized gas. This transformation helped shape the universe we observe today.
Ancient quasars are especially valuable because they act like cosmic time capsules. By studying them, scientists can learn about the earliest galaxies, the first large black holes, and the conditions that existed when the universe was still developing its structure.
The second-oldest quasar identified in Yangโs study was recently examined in greater detail by Silvia Belladitta and colleagues. Their observations showed that the quasar sits inside a dusty, gas-rich galaxy where new stars are forming rapidly. This provides an important clue about what the host galaxies of early supermassive black holes may have looked like.
ESA Euclid Project Scientist Valeria Pettorino described ancient quasars as rare but powerful tools for exploring the early universe. They are not only interesting objects on their own but also help researchers understand how the first generation of galaxies emerged.
Why Euclid Is Important for Quasar Hunting
Euclidโs strength lies in its ability to observe wide regions of the sky with sharp imaging and infrared sensitivity from space. This combination makes it highly effective at detecting rare and distant objects that are difficult to find with other telescopes.
The discoveries were made using data from the Euclid Wide Survey, which is expected to cover more than one-third of the sky when completed. As Euclid continues its mission, it will observe billions of galaxies, map the large-scale structure of the universe, and help scientists study dark matter, dark energy, and the evolution of the cosmos.
The identification of these 31 ancient quasars also required major data-processing efforts by scientists and engineers in the Euclid Consortium. By carefully searching through enormous data sets, the team was able to separate rare, distant quasars from the many other objects captured in Euclidโs images.
Euclidโs discovery marks a major advance in the study of the early universe. By revealing a larger population of quasars from the cosmic dawn, the telescope is giving astronomers a clearer view of how the first galaxies and supermassive black holes formed and evolved.
Journal Reference:
Yang, D., et al. (2026). Euclid: Discovery of 31 new quasars at 6.6 < z < 7.8. Astronomy & Astrophysics. https://doi.org/10.1051/0004-6361/202658883